Not applicable.
Not applicable.
The subject invention relates to medical syringes and syringe actuation apparatuses and more particularly to front-loading medical injectors and syringes for use therewith.
Syringe injection systems have been used in medical procedures for many years. Many such syringes are operated by manually advancing a plunger slidably received within the syringe to pressurize the fluid within the syringe and expel it from the syringe through an opening in the forward end of the syringe. In numerous medical injection procedures, however, accurate control and/or high pressures are required that cannot be achieved via manual syringe operation.
Over the years, a number of syringes and powered injectors for actuating the syringes have been developed for use in medical procedures such as angiography, computed tomography, ultrasound and NMR/MRI. A powered injector typically includes a housing that operably supports a drive member that is constructed for attachment to a plunger contained within a syringe. Many powered injectors contain varying levels of sophisticated control circuitry for controlling the advancement and retraction of the plunger drive member.
Depending upon the pressures required by the injection procedure, some injectors are equipped with pressure jackets for supporting and preventing the body of the syringe from bursting during the injection procedure. Examples of such injectors are disclosed in U.S. Pat. Nos. 5,928,197; 5,865,805; 5,300,031 and 5,738,659. In these devices, the syringe is inserted into the open end of a pressure jacket that is affixed to a mounting plate that is connected to the front of the injector housing. The forward portion of the syringe is equipped with an attachment flange that is formed with threadlike flanges for engagement with corresponding flanges provided around the open forward end of the pressure jacket. The mounting plate is typically pivotally and removably attached to the front of the injector housing. Prior to operation, the mounting plate must be locked to the injector housing by rotating a locking mechanism into locking engagement with a forward protruding pin mounted to the injector housing. Such injectors may also be equipped with sensors positioned within the injector housing and arranged to detect a magnet positioned in a certain position within the mounting plate to inform the control circuit of the type of mounting plate (and corresponding syringe size) that is attached to the injector. Thus, it will be appreciated that such locking mechanism and pressure jacket arrangement can be expensive to manufacture and cumbersome to use. Accordingly, there is a need for a mechanism for attaching a front-loading syringe to a powered injector that does not require the use of expensive and cumbersome locking mechanisms for locking the syringe mounting plate in an injection position.
Syringes that are constructed for use with powered injectors include a plunger for forcing the fluid medium contained within the syringe body through an opening in the forward end of the syringe. Such plungers typically comprise a rigid single-piece core member that is molded from a plastic material. An elastomeric seal is commonly attached to the forward end of the plunger core for achieving a fluid-tight sliding seal between the plunger and the inside surface of the syringe body. An example of such a plunger is disclosed in U.S. Pat. No. 5,902,276. Other core members are of two-piece constructions that generally comprise a forward piece and a rearward piece that is dissimilar from the forward piece. Thus, such two-piece construction requires different molds to be employed for molding each core portion. This molding arrangement results in increased manufacturing costs because two different types of molds must be maintained and operated.
Regardless of the method employed to construct a syringe plunger, the plunger must be properly positioned within the syringe body such that it can be connected with the syringe drive member when the syringe is attached to the powered injector. If the plunger is cocked within the syringe body, it may be difficult to connect the drive member to the plunger. Furthermore, if the plunger is cocked within the syringe body, the seal between the plunger and the syringe body may be compromised which can lead to undesirable leakage between those components. As such, there is a need for a syringe plunger that is easy to manufacture and install and that does not have the problems associated with prior plunger designs.
Some injection procedures also involve the injection of a heated fluid into a patient. To accomplish such task, heater xe2x80x9cblanketsxe2x80x9d have been developed that are designed to snap around the cylindrical syringe body to heat the fluid therein. In general, such heater blankets comprise a flexible resistance heater that is encapsulated in rubber material and is formed in a semi-circular shape for close fitting engagement with the syringe body. The heater blankets are attached, via cable, to an electrical power source. Because the heat is transferred through the syringe body, the efficiency of the heating process is dependent upon the close contact of the heater blanket to the syringe body. The heater blankets are commonly of split design that permits them to be snapped around the body of the syringe. Unfortunately, such construction requires each heater blanket to be formed to accommodate a specific size of syringe body. Therefore, larger heater blankets typically cannot effectively accommodate smaller syringes because they would loosely contact the syringe body and thus compromise heating efficiency. Accordingly, there is a need for an apparatus that can be used in connection with conventional heater blankets to enable one size of heater blanket to be used on a variety of different syringe body sizes.
In accordance with one form of the present invention, there is provided a syringe plunger that comprises a first core half that has first core attachment members and a second core half that is substantially identical to the first core half. The second core half has second core attachment members for complementary engagement with the first core attachment members to interconnect the first core half to the second core half. The plunger core may be provided with an anti-cocking flange that prevents the syringe from becoming axially misaligned within the syringe body which could compromise the seal between the plunger and the syringe body. An alignment flange may also be provided on the plunger which facilitates proper assembly of the plunger into the syringe.
The present invention may also comprise a syringe plunger having a rear attachment portion for engaging an injector drive member. In a preferred embodiment, the rear attachment portion may comprise a blade portion axially aligned on a central axis of the plunger, and an attachment member or button attached to the blade portion. The attachment button is preferably substantially perpendicular to the central axis of the plunger. Preferably the rear attachment portion of the plunger allows the plunger to be placed in a driven state or an undriven state at any position of the plunger within the syringe.
The present invention may also comprise a mounting member for removably affixing a syringe to an injector that contains a driven plunger rod. The mounting member may include a faceplate that has a forward face and syringe attachment members for cooperation with syringe retaining members on the rearward end of a syringe body to removably affix the syringe to the faceplate by axially inserting the rearward portion of the syringe body into an interface formed in the faceplate and rotating the syringe about a syringe axis that is perpendicular to the forward face. The faceplate may be pivotally attachable to the injector housing such that the faceplate is pivotable to an injection position wherein the interface is aligned with the drive rod in the injector. The faceplate may be equipped with a locking mechanism that automatically releasably retains the faceplate in the injection position when it is pivoted to that position.
The present invention may also comprise a locking mechanism for a syringe mounting plate that is pivotally attached to an injector housing and pivotable to an injection position. The locking mechanism may include a locking member on the injector and a retaining member affixed to the mounting plate such that it automatically releasably engages the locking member on the injector when the mounting plate is pivoted to the injection position. In one embodiment, the locking member comprises a pin and the retaining member comprises a spring clip. In another embodiment, the locking member comprises a locking pin and the retention member comprises a spring-biased ball detent.
The present invention may also include a retainer member for retaining a heater blanket in close contact with a syringe body. In one embodiment, the retainer member comprises a split sleeve with an internal diameter that is less than an external diameter of the syringe body.
It is a feature of the present invention to provide a means for mounting a front-loading syringe to a powered injector that is relatively inexpensive to manufacture and easy to install.
It is another feature of the present invention to provide a unique and novel plunger construction that is easier to manufacture than prior single and two-piece plunger designs.
It is yet another feature of the present invention to provide a plunger that is maintained in axial alignment with the syringe body to prevent leakage between the syringe and the plunger.
Yet another feature of the present invention is to provide a plunger that can be automatically installed in a syringe body in a predetermined orientation that facilitates engagement of the plunger with a plunger drive rod when the syringe is coupled to the injector.
It is still another feature of the present invention to provide an apparatus that enables a conventional syringe heater blanket to be used effectively on a variety of different syringes.
Accordingly, the present invention provides solutions to the shortcomings of prior syringe and powered injector systems. Those of ordinary skill in the art will readily appreciate, however, that these and other details, features and advantages will become further apparent as the following detailed description of the embodiments proceeds.